类型为 \"User\" 的字段 \"me\" 必须选择子字段

Question

嗨，我正在努力学习 GraphQL 语言。我有以下代码片段。

// Welcome to Launchpad!
// Log in to edit and save pads, run queries in GraphiQL on the right.
// Click "Download" above to get a zip with a standalone Node.js server.
// See docs and examples at https://github.com/apollographql/awesome-launchpad

// graphql-tools combines a schema string with resolvers.
import { makeExecutableSchema } from 'graphql-tools';

// Construct a schema, using GraphQL schema language
const typeDefs = `
    type User {
        name: String!
        age: Int!
    }

    type Query {
        me: User
    }
`;

const user = { name: 'Williams', age: 26};

// Provide resolver functions for your schema fields
const resolvers = {
  Query: {
    me: (root, args, context) => {
      return user;
    },
  },
};

// Required: Export the GraphQL.js schema object as "schema"
export const schema = makeExecutableSchema({
  typeDefs,
  resolvers,
});

// Optional: Export a function to get context from the request. It accepts two
// parameters - headers (lowercased http headers) and secrets (secrets defined
// in secrets section). It must return an object (or a promise resolving to it).
export function context(headers, secrets) {
  return {
    headers,
    secrets,
  };
};

// Optional: Export a root value to be passed during execution
// export const rootValue = {};

// Optional: Export a root function, that returns root to be passed
// during execution, accepting headers and secrets. It can return a
// promise. rootFunction takes precedence over rootValue.
// export function rootFunction(headers, secrets) {
//   return {
//     headers,
//     secrets,
//   };
// };

要求：

{
  me
}

回复：

{
  "errors": [
    {
      "message": "Field \"me\" of type \"User\" must have a selection of subfields. Did you mean \"me { ... }\"?",
      "locations": [
        {
          "line": 4,
          "column": 3
        }
      ]
    }
  ]
}

有谁知道我做错了什么？如何解决？

Answer 1

From the docs:

A GraphQL object type has a name and fields, but at some point those fields have to resolve to some concrete data. That's where the scalar types come in: they represent the leaves of the query.

GraphQL 要求您以仅 returns 具体数据 的方式构建查询。每个字段最终都必须解析为一个或多个标量（或枚举）。这意味着您不能只请求一个解析为某种类型的字段而不指明您想要返回该类型的哪些字段。

这就是您收到的错误消息告诉您的内容——您请求了一种 User 类型，但您没有告诉 GraphQL 至少一个字段从该类型返回。

要修复它，只需更改您的请求以包含 name，如下所示：

{
  me {
    name
  }
}

... 或 age。或两者。但是，您不能请求特定类型并期望 GraphQL 为其提供所有字段——您将始终必须为该类型提供选择的（一个或多个）字段。

类型为 \"User\" 的字段 \"me\" 必须选择子字段

Field \"me\" of type \"User\" must have a selection of subfields

javascript

graphql

graphql-js